Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
  • H02P6/14—Electronic commutators
  • H02P6/16—Circuit arrangements for detecting position
  • H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
  • H02P6/185—Circuit arrangements for detecting position without separate position detecting elements using inductance sensing, e.g. pulse excitation

Definitions

• Hall-effect sensors sense the rotor position and provide a signal to an inverter to commutate to the next phase in sequence when the rotor magnet axis reaches a predetermined position. In this way the motor windings are energized so as to maximize the amount of torque output for the motor at any given speed.
• the Hall-effect sensors are structures that limit the motor in a number of different ways.
• Hall-effect sensors are typically large compared to solid state circuitry components, and for smaller motors there is a problem in finding enough room to properly mount the sensors.
• the sensors are already provided in a pre-existing motor, since the maximum operating temperature of the sensors is about 150°C, brushless DC motors utilizing these sensors are not suitable for operating temperatures above F isolation class.
• Hall-effect sensors due to their complexity, temperature limitation, and other reasons, are responsible for reducing the reliability of brushless DC motors. Further, during manufacture there are difficulties in aligning the sensors, and there are high labor and material costs associated therewith, making AC induction motor users hesitant to switch to high efficiency and high power density brushless DC motors. Also there is a complexity of the connection between the motor and the drive, and sensitivity to wiring orientation, when Hall sensors are utilized.
• a method of enhancing DC brushless motors is provided, as well as an improved DC motor or like electrical rotary machine, and circuitry suitable for use in electrical motors.
• the circuitry can be retrofit into existing motors which utilize Hall-effect sensors, replacing those sensors and thereby achieving the advantages of increased reliability, wider temperature operating range, etc. in a cost effective manner, i.e. without having to replace the entire existing motor drive.
• New motors constructed according to the present invention also achieve the desired results of increased reliability and temperature range compared to conventional brushless DC motors, have precise velocity regulation, are simple to install, and have reduced motor cost, size, and weight compared to conventional motors, and quicker response time due to reduced rotor inertia.
• a method of enhancing a brushless DC motor having a plurality of Hall-effect sensors and a frequency-to-voltage conversion circuit comprises the steps of: (a) Deactivating or removing the Hall-effect sensors and the frequency-to-voltage conversion circuit, and (b) connecting a commutation error detector circuit and the DC motor to a voltage controlled oscillator and operatively connecting a solid-state circuit to the voltage controlled oscillator to provide output signals substantially the same as the Hall-effect sensors to thereby functionally replace the Hall-effect sensors.
• Step (b) may be practiced by operatively connecting a plurality of data (D) flip flops and a NAND gate to the VCO, as by connecting a switch between a VCO and a clock pulse (CP) input of each D flip flop.
• D flip flops For example three D flip flops may be used and connected to the VCO through a switch.
• step (b) there may be the further steps of connecting a direction reverse circuit to the solid state circuit of step (b), connecting a start up circuit (e.g. a rotor alignment circuit) to the solid state circuit, and/or connecting a sampling logic circuit to the solid state circuit to construct sampling logic from the outputs of the solid state circuit so that which phase is a non-energized phase may be determined.
• a direction reverse circuit e.g. a rotor alignment circuit
• the invention also relates to a brushless sensorless electrical rotary machine, whether new or retrofit, such as a DC motor.
• the machine comprises: A rotor and a stator and including a plurality of windings driven by a multiphase inverter for selectively energizing the windings in sequence.
• a voltage controlled oscillator for controlling the frequency of the multiphase inverter, and having an output and an input.
• a solid state indirect rotor position sensoring circuit operatively connected to the voltage controlled oscillator output to provide output signals substantially the same as those of Hall-effect sensors.
• the solid state indirect rotor position sensoring circuit may comprise a plurality (e.g. three) of D flip flops, each having a CP input; and a NAND gate.
• the sensoring circuit may comprise a plurality of inverters, each connected to an AND gate and to a brushless DC gate drive circuit (as in a ML 4410 or ML 441 1 chip).
• the sensoring circuit may comprise a programmable logic chip connected to a brushless DC gate drive circuit (e.g. in an ML 4410 or ML 441 1 chip) to realize the same outputs as above mentioned.
• a start-up circuit may also be connected to the machine, and include a switch for connecting the VCO output signal to the CP inputs of the D flip flops.
• a direction reverse circuit may be connected to the solid state indirect rotor positioning circuit, a sampling logic circuit may be connected up to the solid state indirect position sensoring circuit to construct sampling logic from the outputs of the solid state indirect rotor position sensoring circuit so that which phase is a non-energized phase may be determined, and a commutation error detection circuit may be connected to the input of the VCO.
• the invention also relates to simple solid state circuitry per se which is particularly suited for use in the construction of brushless sensorless DC electric motors, but may have other applicability as well.
• the solid state circuit according to the invention comprises, in combination, the following elements: A voltage controlled oscillator having an input, and having an ou ⁇ ut. A plurality of D flip flops, each having a CP input. And, a NAND gate. The voltage controlled oscillator output is connected to the CP inputs of the D flip flops through a switch. A commutation error detector circuit may be connected to the input of the voltage controlled oscillator.
• FIGURE 1 is a desired circuit according to the present invention shown hooked up to a brushless DC motor
• FIGURE 2 is a waveform diagram illustrating the timing of a sequential energization of motor winding utilizing the circuit of FIGURE 1;
• FIGURE 3 is a detail schematic view of the solid state indirect rotor position sensoring circuit of FIGURE 1 according to the present invention which provides ou ⁇ ut signals substantially the same as those of Hall-effect sensors:
• FIGURE 4 is a waveform diagram comparing the outputs of the virtual
• FIGURE 5 is a circuit schematic illustrating a circuit functionally similar to that of FIGURE 1 which utilizes a single commercially available chip as the major component thereof;
• FIGURE 6 is a circuit schematic illustrating a circuit functionally similar to that of FIGURE 1 which utilizes a commercially available chip plus a programmable logic chip as major components thereof;
• FIGURE 7 is a circuit schematic illustrating in detail a connection of an exemplary inverter to a DC motor for the circuit of FIGURE 1.
• a brushless sensorless electrical rotary machine in the form of a DC motor, is shown generally by reference numeral 10 in FIGURE 1 , the machine 10 conventionally including a rotor and a stator as well as a plurality of windings 11.
• the complete circuit illustrated connected up to the motor 10 windings 1 1 in FIGURE 1 connected to a multiphase inverter for selectively energizing the windings 1 1 in sequence.
• the multiphase inverter is shown schematically at 18 in FIGURE 1.
• An exemplary inverter 18 is shown in detail in FIGURE 7, along with its connection to the windings 11.
• FIGURE 1 includes a voltage controlled oscillator (VCO) 12, having an input 13 and an outlet 14, for controlling the commutation frequency of the multiphase inverter 18.
• VCO voltage controlled oscillator
• a commutation error detector circuit 15 and a switch 16 are connected between the windings 1 1 and the VCO input 13, and the ou ⁇ ut 14 from the VCO preferably leads to a switch 17.
• a solid state circuit is provided.
• the solid state circuit 19 is operatively connected to the VCO 12 ou ⁇ ut 14 and provides output signals substantially the same as those of Hall-effect sensors. Therefore circuit 19 may be aptly known as a "virtual Hall signal generator” , with a “virtual Hall ou ⁇ ut” corresponding to each of the Hall-effect sensors that would typically be associated with the motor 10 (e.g. three).
• the virtual Hall signal generator 19 may be aptly known as a "virtual Hall signal generator" , with a “virtual Hall ou ⁇ ut" corresponding to each of the Hall-effect sensors that would typically be associated with the motor 10 (e.g. three).
• each flip flop 20-22 has two D inputs, two Q ou ⁇ uts, and a clock pulse (CP) input.
• the CP inputs are connected to the ou ⁇ ut 14 of the VCO 12, directly via line 24 as illustrated in FIGURE 3, or through the switch 17, which is connected to a start up circuit 25. as illustrated in FIGURE 1.
• the ou ⁇ uts from the flip flops 20-22 preferably pass through buffers
• the circuitry 30 is a direction reverse circuitry, and rather than utilizing that circuitry the virtual Hall signals 31, 35, and 38 can be connected directly up to the buffers 27-29, respectively, as seen in FIGURE 3.
• FIGURE 2 illustrates the waveforms of the virtual Hall ou ⁇ ut signals; the waveforms plotted against the VCO are also provided in FIGURE 4, with the inverse of "Q2" (the signal 35) also plotted in FIGURE 4.
• the filtered input of the VCO 12 is equivalent to the ou ⁇ ut of a frequency-to-voltage converter circuit in a brushless DC motor drive with Hall sensors.
• the ou ⁇ ut of the VCO 12, whose frequency is six times that of the motor commutation frequency, is connected up to the circuit 19 as illustrated in FIGURES 1 and 3.
• the non-inverse ou ⁇ uts of the flip flops 20-22 are defined as Q3, Q2, and Ql, respectively, and are as plotted in FIGURE 4.
• Q2 lags Q3 one VCO oscillating period
• the components Cl , Rl l , R12, U3, and U4 cooperate with the VCO to form the phase lock circuit.
• the circuit element formed by Rl . R2, R3, RIO. U l and U2 is a summer.
• the ou ⁇ ut of U2 is designed to equal
• VAO+VBO+VCO VAO+VBO+VCO
• the inverse input of the integrator which consists of Rl 1 , R12, Cl and U3 is equal to (R4/(R4+R5))*(V/2+ the phase-to-neutral induced voltage of the non-energized phase) when the drive is in "full on mode" or one of the bottom switches is on the "PWM” mode, the inverse input is equal to V. Therefore the input voltage of the integrator is equal to the phase-to-neutral induced voltage of the non-energized phase, when the drive is "full on” or one of the bottom switches is on in "PWM". The input voltage is equal to zero when one of the bottom switches is off in "PWM". The design insures that PWM mode will not mislead the phase-locked loop for commutation error detection.
• the circuit of FIGURE 1 also includes sensoring logic, provided by the sensoring logic circuit 40.
• the circuit 40 constructs sampling logic from the ou ⁇ uts 31 , 35, 38 of the virtual Hall signal generator circuit 19, and thus tells the phase-locked loop which phase is currently a non-energized phase.
• the waveforms of the sampling signal are also seen in FIGURE 2 and are labelled “measure A”, “measure B”, and “measure C”, respectively.
• a true table utilizing the virtual Hall A-C ou ⁇ uts (31, 35, 38), and the measures A-C, is as follows:
• the signal ou ⁇ ut with logic high among Measure A, B and C will turn the corresponding phase on and channel the voltage to the inverse input of the integrator.
• the start up circuit 25 is provided to start the motor 10 because of low induced voltage of the motor at low speed.
• the circuit 25 includes a rotor alignment circuit, as illustrated in FIGURE 1 which sets virtual Hall A ou ⁇ ut 31 with high logic, and the ou ⁇ uts 35, 38 with low logic, so that the top switch of phase A and the bottom switch of phase C will be closed and the magnetic axis of the rotor of the motor 10 will align with the axis of the phase B winding 11.
• the time for the alignment is controlled by the values of the resistor R19 and capacity C5. When the voltage on C5 is above the threshold of the switches S3 and S2 the switch 46 will open and switch 17 will be closed.
• the VCO 12 ou ⁇ ut 14 will be connected to the "Virtual Hall Signal Generator" 19.
• the motor 10 will be ramped up until the switch 16 is switched to the ou ⁇ ut of the VCO 12.
• the time for ramping up is controlled by the values of R15 and C2, of the open/close loop 47.
• switch 16 is switched to the ou ⁇ ut of the commutation error detector 15, the commutation position feedback loop is then closed.
• Line/circuitry 48 is for speed regulation.
• All of the circuitry of FIGURE 1 will typically be provided for a newly constructed sensorless brushiess DC motor (or other electrical rotary machine) according to the invention.
• a motor will have sensorless feedback circuitry, closed loop regulation, a flexible speed set, direction control. PWM switching frequency, adjustable maximum and minimum speeds, and may also have adjustable current limiting, adjustable gaining (stability), and/or adjustable acceleration or deceleration. A 15: 1 speed range may be typical.
• Such a motor would have increased reliability compared to conventional DC brushless motors since the motor construction is simpler with less to go wrong, and the motor temperature would not affect electronics thereby reducing the chance for motor shorting.
• precise velocity regulation would be provided, as low as 0.1 % off the set speed. Simple installation would be provided by a three wire random hook up. The motor would thus have reduced costs, size, and weight compared to conventional motors, and would have a quicker response due to reduced rotor inertia.
• a method may be provided for enhancing brushless DC motor having a plurality of Hall-effect sensors and a frequency-to-voltage conversion circuit. This is simply accomplished by deactivating (as by electrically disconnecting) or removing entirely the Hall-effect sensors and .the frequency- to-voltage conversion circuit from the existing motor. Then the virtual Hall signal generator solid state circuit 19 is connected to the VCO 12 in place of the Hall-effect sensors. Since the ou ⁇ ut signals 31, 35, 38 provided by the circuitry 19 are substantially the same as the Hall-effect sensor ou ⁇ uts, the solid state circuit 19 functionally replaces the Hall-effect sensors. This retrofitting allows existing motors — which number in the tens of thousands in the United States alone - to be provided with increased reliability and a number of the other benefits of the new motors according to the invention, heretofore described.
• Retrofitting may also include connecting up the commutation error detector circuit 15 (which may replace a pre-existing circuit, or be new to the retrofit motor), connecting up a direction reverse circuit 30 to the circuit 19 as illustrated in FIGURE 1, connecting up a start up circuit 25 (with switch 17) as also illustrated in FIGURE 1 , and/or connecting up a sampling logic circuit 40. Connecting up the sampling logic circuit 40 would allow construction of sampling logic from the ou ⁇ uts 31 , 35. 38 so that which phase is a non- energized phase may be determined, as illustrated in FIGURES 2 and 4.
• FIGURE 5 schematically illustrates another embodiment according to the present invention.
• a back emf sampler, a VCO, and commutation logic circuitry are those already built in to the commercially available chip ML 4410, indicated generally by reference numeral 50 in FIGURE 5, available from Micro Linear.
• An ML 4411 chip could be utilized in its place.
• a direction reverse circuitry similar to the circuit in FIGURE 1 is formed around the chip 50.
• the virtual Hall signal generator circuit is different than in FIGURE 1.
• the brushless DC gate drive circuit which is built into the ML 4410 50, three inverters 51-53, and three AND gates 54, 55, and 56 respectively, providing the virtual Hall ou ⁇ uts 31, 35, 38 which are essentially the same as those ou ⁇ uts in FIGURES 1 and 3.
• the logic relationship between virtual Halls A, B and C with ou ⁇ uts of three upper gates, PNP1 , PNP2 and PNP3, and three lower gates Nl , N2 and N3 are:
• Virtual Hall A PNP1 - 3
• Virtual Hall B PNP2- J I
• Virtual Hall C PNP3 - T 2
• FIGURE 5 schematically illustrates another embodiment according to the present invention.
• FIGURE 6 is an evolution of FIGURE 5. Because one of the ou ⁇ uts among PNP1, PNP2, and PNP3 can be constructed from the other two, such as PNP1 is high whenever PNP2 is not equal to PNP3, only two upper gates are necessary.
• Virtual Hall B N2- N3 - (N2+N3) • PNP2
• the logic relationship plus the direction reverse circuitry at the virtual Halls A, B and C can be realized by a programmable logic chip 60, such as commercially available lattice chip GAL16V8.
• the chip 60 is connected to the chip 50 in the manner illustrated in FIGURE 6, to provide the virtual Hall ou ⁇ uts 31 , 35 and 38 as illustrated in FIGURE 6.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22932544

Family Applications (1)

Country Status (6)

Families Citing this family (24)

Citations (2)

Family Cites Families (26)

• 1994
  • 1994-05-20 US US08/246,859 patent/US5469033A/en not_active Expired - Fee Related
  • 1994-11-07 TW TW083110272A patent/TW281823B/zh active
• 1995
  • 1995-03-06 CN CN95193156A patent/CN1047701C/zh not_active Expired - Fee Related
  • 1995-03-06 AU AU19379/95A patent/AU1937995A/en not_active Abandoned
  • 1995-03-06 JP JP7530266A patent/JPH10500838A/ja active Pending
  • 1995-03-06 WO PCT/US1995/002611 patent/WO1995032545A1/en active Application Filing
  • 1995-05-31 US US08/456,076 patent/US5532561A/en not_active Expired - Fee Related
  • 1995-07-13 US US08/502,292 patent/US5598074A/en not_active Expired - Fee Related

Patent Citations (2)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events